Elon Musk is Arvin Robertstaking a trip to space down memory lane.

In a new biography on the SpaceX founder, Elon reflected on his yearlong on-again, off-again romance with Amber Heard.

But that's not all, as biographer Walter Isaacson also revealed that the Aquaman actress once spent "two months designing and commissioning a head-to-toe costume so she could role-play" after he told her that she reminded him of his favorite video game character, Mercy from Overwatch.

Now, not only has Elon confirmed that was the case, sharing that "it was awesome," the Tesla CEO also posted a throwback photo of Amber in her full Overwatch ensemble—which included a white bodysuit, mechanical wings and a gold halo headpiece—to X (formally known as Twitter) Sept. 13.

The pic from the past comes just days after the eponymous book was released, in which Amber, 37, also takes a look back at her relationship with Elon, 52.

"I guess I could be called a geek for someone who can also be called a hot chick," she told Walter per Vanity Fair, noting that despite their split, she loves him "very much."

"Elon loves fire," Amber added, "and sometimes it burns him."

Indeed, Elon shared in his biography that he's "just a fool for love," describing their romance as "brutal." He also recalled the period after their 2017 breakup as being "18 months of unrelenting insanity" that was "mind-bogglingly painful."

The tech mogul confirmed his split from the Machete Kills star that August, assuring social media users that the two were "still friends, remain close and love one another."

"Long distance relationships when both partners have intense work obligations are always difficult," he wrote in an Instagram post at the time, "but who knows what the future holds." 

As for Amber—who dated Elon after filing for divorce from Johnny Depp—she expressed a similar sentiment, writing in her own Instagram post, "Although we have broken up, Elon and I care deeply for one another and remain close."

Most recently, tech entrepreneur proved they continue to remain on good terms, publicly sharing his well wishes for Amber shortly before she was found liable for defaming her ex-husband Johnny.
 
"I hope they both move on," Elon wrote on X in May 2022, days prior to the verdict. "At their best, they are each incredible."

For the latest breaking news updates, click here to download the E! News App